The man can be seen clearly on surveillance video at Oscar's Estate Jewelry on Saturday just before 11 a.m.

The video shows the man standing over a display case and frequently glancing around to see if anyone was watching. He then worked hard to nudge the sliding door to the case open, but when the owner neared, he moved away, officials said.

The thief then paced around until he finally managed to snatch the necklace and take off.

Authorities said the necklace is 18kt gold with a half carat of diamonds in a heart-shaped pattern.

Officials said the man is described as standing 5 feet 8 inches to 5 feet 11 inches tall and is heavy-set with a pronounced stomach. He has brown hair and a beard but no mustache.

The thief was wearing a blue Chicago Bears shirt and baggy checkered shorts. He has tattoos on the underside of both forearms, officials said.

Anyone who recognizes the man is asked to call the Sheriff's Office at 386-323-0151.